1. Field of the Invention
This invention relates in general to vehicle locating systems, and more specifically to a vehicle locating system which utilizes mobile tracking devices having global positioning.
2. Description of the Related Art
There are a number of vehicle location systems that are in use which provide stolen vehicle tracking and/or locating services. One such vehicle tracking system uses mobile tracking units located in police cars which allow the police to track and locate a stolen vehicle. In such a system, the owner of the stolen vehicle reports to the police network when a vehicle is stolen. The police network activates a miniature transmitter located within the stolen vehicle which allows the police to track the stolen vehicle. The police are then able to locate and recover the stolen vehicle when the stolen vehicle remains within the existing police network. The ability to track and locate the stolen vehicle in such a system is dependent largely on the number of police vehicles participating in the tracking and the size of the area which can be covered by the number of police vehicles available.
Another such vehicle location system uses stationary towers on top of buildings on which are installed directional antennas which are used to triangulate the location of the stolen vehicle. Such stationary tower sites are extremely expensive to set up and maintain. In addition, it is very hard to find transmitting/receiving sites in large metropolitan areas which are suitable for such stationary tower sites. And even after a location within the city is found upon which to erect a stationary tower, the location could turn out to be full of high level interfering signals so close to the operating band that it would be impossible to filter them out. This problem is especially true in many third world and emerging countries, as there are no government bodies in place which carry the enforcing powers that belongs to the FCC in the U.S. Consequently, there is no control over how many antennas or what operating frequencies are present at any of the stationary antenna sites.
Faced with all these problems, what is needed is a vehicle location system that would allow drastic cuts in the infrastructure cost by reducing the number of sites needed within the city without sacrificing system reliability.